1. Field of the Invention
The present invention relates to the field of esters and more particularly to esters with bioresistant, fungal resistant and antimicrobial/antifungal properties.
2. Description of the Problem Solved by the Invention
Due to environmental regulation, the use of tin, mercury, lead, and other heavy metals to control the growth of microbes in organic systems is now prohibited. In particular metal working fluids (MWF)and metal working fluid bases suffer a failure mode when attacked by microbes. The problem is especially acute in water extendable and emulsion MWF systems. The attack of the microbes on the MWF base causes the pH of the system to drop, which destabilizes the emulsion and also increases the corrosion of metal parts that are exposed to the attacked fluid. Aside from the obvious problems that microbes cause in MWFs, operator health issues also arise due to continuous exposure to high levels of bacteria. Current systems in place such as pigment dispersants and MWFs include the addition of biocides to the fluid to prevent the bacteria from breaking down the MWF. One common biocide in use is the family of isothiazolinones. This product is generally hazardous to handle and causes sensitization in many people when exposed repeatedly. The sensitization often takes the form of itching all over the body, or hives when any part is in contact with the isothiazolinone. Additionally, the isothiazolinone family is relatively unstable at the alkaline pH that most MWFs are maintained at. This then requires the operator to add more material on a regular basis. Also, the microbes develop a tolerance to isothiazolinones. This again requires the operator to increase the amount of the isothiazolinone in the system.
A second biocide technology is the use of formaldehyde condensates. These materials are generally hazardous, but do not lead to sensitization of the operators in contact with the MWF. The formaldehyde condensates do contribute to free formaldehyde in the workplace, but the results are not consistent as to how much formaldehyde they contribute to the workplace atmosphere. Most formaldehyde condensates are volatile and evaporate. This requires their replenishment on a regular basis even when they are not consumed.
What is needed is a system that uses an ester as the MWF base that is not susceptible to microbial attack. The material fails to act as a food source for the microbes that are able to digest the current MWF bases.